This invention relates to pneumatic actuators.
Pneumatically-actuated devices are, of course, very widely used in all sorts of fields, especially in the control field.
Hitherto, it has been conventional practice to control such devices, such as fluid flow regulators, electrically using, for example, so-called I/P converters which produce varying pneumatic outputs in response to varying electrical input signals. By using such converters, remote and/or automatic control is possible. However, they do have disadvantages, especially as regards their response times, their susceptibility to electrical "noise" and, because of the need for relatively high power electrical control signals, their unsuitability for use in hazardous environments.